ABSTRACT
The mutagenicity of airborne particulate matter at three different sites within the São Paulo urban area and the Cubatão industrial area, São Paulo State, Brazil, was evaluated using the Salmonella mutagenicity assay over a year's period (June 1990-May 1991). Total suspended particles (TSP) were collected using a Hi-vol sampler and extracted with methylene chloride by ultrasonication. Pooled seasonal extracts were tested using S. typhimurium TA98 and TA100 with and without metabolic activation (S9) and TA98NR and TA98/1,8-DNP6 without metabolic activation. Organic extracts of the samples with the highest monthly TSP concentration were also assayed for mutagenicity. All samples collected at São Paulo and Cubatão showed mutagenicity with strain TA98, and in general the addition of S9 did not modify the mutagenic response, suggesting the prevalence of direct-acting frameshift mutagens in the atmosphere of these sites. The mutagenicity detected in the urban areas of São Paulo (mainly downtown) was much higher than in the Cubatão industrial area and similar to the more urbanized cities in the world, where vehicle emissions are the major pollution source. Results obtained with the strains TA98NR and TA98/1,8-DNP6 suggested the presence of mononitro- and dinitroarenes contributed to the mutagenicity of these atmospheric samples. A seasonal variation was observed with higher levels of frameshift mutagens during Spring in São Paulo and Summer in Cubatão. During the Winter, more significant responses were found with strain TA100 in the presence of S9 at all sites. Monthly samples presented high levels of mutagenicity during the period of June to November. Results from this research provide support for Air Pollution Control Programs in the detection of the more potent organic mutagenic compounds in the atmosphere and may help in the establishment of priorities for control and regulatory actions.
